#include "beep.h"

// 蜂鸣器 --> PB6--> TIM4_CH1 --> APB1
void  hal_beep_tim4_init(void)
{
	// 1. 设置GPIOB，TIM4的时钟使能   RCC_MP_AHB4ENSETR[1]  RCC_MP_APB1ENSETR[2]
	RCC->MP_AHB4ENSETR = (0x1 << 1);
	RCC->MP_APB1ENSETR = (0x1 << 2);
	// 2. 设置PB6引脚为复用功能       GPIOB_MODER[13:12]
	GPIOB->MODER &= (~(0x3 << 12));
	GPIOB->MODER |= (0x2 << 12);
	// 3. 设置PB6引脚为TIM4_CH1功能   GPIOB_AFRL[27:24]
	GPIOB->AFRL &= (~(0xF << 24));
	GPIOB->AFRL |= (0x2 << 24);
	// 4. 设置预分频寄存器，TIM4_PSC[15:0] = 208   // CK_PSC = 209MHz  
	// 		提供给TIM4的时钟源的频率是209MHz
    TIM4->PSC = 208;
	// 5. 设置PWM方波的最终的周期  TIM4_ARR[16:0] = 1000
	// 		得到一个1000-2000Hz的方波
	TIM4->ARR = 1000;
	// 6. 设置PWM方波的占空比   TIM4_CCR1[16:0] = 700
	TIM4->CCR1 = 700;
	// 7. 设置TIM4_CH1通道为PWM1模式  
	// 		TIM4_CCMR1[16] = 0b0  TIM4_CCMR1[6:4] = 0b110   // pwm模式1  = 0b0110
	TIM4->CCMR1 &= (~(0x1 << 16));
	TIM4->CCMR1 &= (~(0x7 << 4));
	TIM4->CCMR1 |= (0x6 << 4);
	// 8. 设置TIM4_CH1通道使能TIMx_CCR1预加载使能寄存器
	// 		TIM4_CCMR1[3] = 0x1
	TIM4->CCMR1 |= (0x1 << 3);
	// 9. 设置TIM4_CH1通道输出PWM方波的极性，
	// 	  TIM4_CCER[1] = 0x1 or 0x0
	// TIM4->CCER |= (0x1 << 1);
	TIM4->CCER &= (~(0x1 << 1));
	// 10. 设置TIM4_CH1通道的输出使能位，输出PWM方波 
	// 		TIM4_CCER[0] = 0x1 
	TIM4->CCER |= (0x1 << 0);
	// 11. 设置TIM4_CH1通道的TIMx_ARR预装载寄存器的缓冲区的使能
	// 		TIM4_CR1[7] = 0x1 
	TIM4->CR1 |= (0x1 << 7);
	// 12. 设置定时器的计数方式，边沿对齐
	// 		TIM4_CR1[6:5] = 0x0 
	TIM4->CR1 &= (~(0x3 << 5));
	// 12 设置定时器计数的方向，采用递减计数/递增计数 
	// 		TIM4_CR1[4] = 0x0
	TIM4->CR1 &= (~(0x1 << 4));
	// 13. 使能TIM4_CH1计数器 
	// 		TIM4_CR1[0] = 0x1
	TIM4->CR1 |= (0x1 << 0);
}
